Many years ago I read a sci-fi book where it followed the activities of a very wealthy family that would make investments on different planets and then (due to time dilation of close to light speed travel) return to the original planets many hundreds of years later (and be many billions of creds richer).

Anyone know of what book this was?

[edit] I read the book sometime in the 70s. It was at least a decade or two before I read Ender's Game, so that wasn't it.

I checked the Wiki for the other books mentioned below. So far none are even close - sorry (but good choices). Forever War also has compound interest from unpaid salaries but that wasn't it either.

And the financial empire's various investments was a major part of the plot.

I'll post if I find the answer.[/edit]

  • 2
    The Compound Interest Time Travel Gambit page (warning TVTropes!) lists 2 works that might be possibilities: Steven Baxter's Manifold: Space and Card's Ender series. (Though TBH, I don't recall it in the latter so it may not be an important plot point.)
    – DavidW
    Nov 29, 2019 at 22:27
  • 1
    How clearly do you remember the plot? This a very minor plot point in the Hyperion series, but it’s described in a monologue as something that happened in the past: it’s not shown “on screen”. Nov 29, 2019 at 22:55
  • @DavidW, you should make it an answer.
    – Dima
    Nov 30, 2019 at 18:48
  • @DavidW : I do recall it in the latter, though it was hardly a high profile plot element, more of a little bit of random background erata that got a mention in passing, in 'speaker for the dead' he had to declare his taxes for the first time (having passed 18, in his relative time frame, or something), the level of his current wealth & the reasons for it were mentioned then.
    – Pelinore
    Dec 1, 2019 at 6:29
  • FWIW, having finally read Manifold: Space, it's not a match. The compound interest trick only works once, then the government starts confiscating the assets of travellers, who aren't around to defend them.
    – DavidW
    Feb 9, 2020 at 22:14

2 Answers 2


Something similar happens in Neptune’s Brood, by Charles Stross.

Characters travel at light speed by transmitting a body spec and brain state via laser, and the whole book features debt, interest, liquidity, and other financial concepts and repercussions of vast distance and light speed limitations quite centrally.

  • 2
    Could you edit this to explain how it matches?
    – TheLethalCarrot
    Nov 30, 2019 at 8:45

Could it be the Ender series by Orson Scott Card? After the events of Ender's Game, the main character leaves Earth and travels to other planets, accumulating wealth thanks to time dilation.

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